The Critically Complex World of Cars' Sparky Bits

Your most expensive piece of electronics probably is not your flat panel TV or your computer. More likely, it's your car, which can pack 50 microprocessors to control everything from the fuel mix to the rearview mirrors.

The recalls and other technical problems besetting Toyota in the last few weeks highlight the risks of relying on electronics instead of the mechanical rods and cables that controlled vehicles for most of the 20th century.
Driving by Wire

For many years, a car's gas and brake pedals were connected directly to the throttle and the brake assembly. Now computers and electronic sensors govern many of those functions, as well as a vehicle's exhaust system, its inside temperature and a host of other operations.

Those design changes were reviewed this week when the National Highway Traffic Safety Administration began looking into 124 reports from consumers that their Toyota Priuses momentarily lost braking ability while traveling over uneven roads, potholes or bumps. Four of the reports involve crashes.

The Prius problem is part of a broader issue for Toyota: Accelerators in its non-hybrid cars can get trapped under floor mats or become stuck on their own and fail to return to the idle position. Toyota has recalled eight top-selling models, involving 2.3 million cars in the U.S. alone.

The wider problems appear to be conventional mechanical issues, but Transportation Secretary Ray LaHood said his department would undertake a broad review of whether automobile engines could be disrupted by electromagnetic interference caused by power lines or other sources.